package main

import "fmt"

type void struct{}

func main() {
	go.set := make(map[string]void)
	var empty void
	go.set["a"] = empty
	go.set["b"] = empty
	go.set["b"] = empty
	go.set["c"] = empty
	delete(go.set, "c")
	fmt.Println(go.set)
	keys := make([]string, 0, len(go.set))
	for k := range go.set {
		keys = append(keys, k)
	}
	fmt.Println(keys)
	_, v := go.set["c"]
	fmt.Println(v)
}